netdev - Re: [PATCH 05/11] dt-bindings: net: can: Add serdev LIN bus dt bindings

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Message-ID: <77d0b2c62aad02c7c6f291676673b672ab35528a.camel@hexdev.de>
Date: Thu, 02 May 2024 07:26:59 +0200
From: Christoph Fritz <christoph.fritz@...dev.de>
To: Krzysztof Kozlowski <krzk@...nel.org>, Oliver Hartkopp
 <socketcan@...tkopp.net>, Marc Kleine-Budde <mkl@...gutronix.de>, Vincent
 Mailhol <mailhol.vincent@...adoo.fr>, "David S . Miller"
 <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski
 <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, Rob Herring
 <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Jiri Kosina <jikos@...nel.org>, Benjamin Tissoires
 <bentiss@...nel.org>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Jiri
 Slaby <jirislaby@...nel.org>
Cc: Andreas Lauser <andreas.lauser@...cedes-benz.com>, Jonathan Corbet
	 <corbet@....net>, linux-can@...r.kernel.org, netdev@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-input@...r.kernel.org, 
	linux-serial@...r.kernel.org
Subject: Re: [PATCH 05/11] dt-bindings: net: can: Add serdev LIN bus dt
 bindings

Hello Krzysztof,

 thanks for your feedback, please see my answers below.

On Mon, 2024-04-22 at 09:54 +0200, Krzysztof Kozlowski wrote:
> On 22/04/2024 08:51, Christoph Fritz wrote:
> > Add documentation of device tree bindings for serdev UART LIN-Bus
> > devices equipped with LIN transceivers.
> 
> A nit, subject: drop second/last, redundant "dt bindings". The
> "dt-bindings" prefix is already stating that these are bindings.
> See also:
> https://elixir.bootlin.com/linux/v6.7-rc8/source/Documentation/devicetree/bindings/submitting-patches.rst#L18

OK

> 
> > 
> > Signed-off-by: Christoph Fritz <christoph.fritz@...dev.de>
> > ---
> >  .../bindings/net/can/linux,lin-serdev.yaml    | 29 +++++++++++++++++++
> >  1 file changed, 29 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/net/can/linux,lin-serdev.yaml
> > 
> > diff --git a/Documentation/devicetree/bindings/net/can/linux,lin-serdev.yaml b/Documentation/devicetree/bindings/net/can/linux,lin-serdev.yaml
> > new file mode 100644
> > index 0000000000000..cb4e932ff249c
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/net/can/linux,lin-serdev.yaml
> > @@ -0,0 +1,29 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/net/can/linux,lin-serdev.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Linux serdev LIN-Bus Support
> 
> This looks like Linux binding, but we expect here description of hardware.

OK


> > +
> > +description: |
> > +  LIN-Bus support for UART devices equipped with LIN transceivers,
> > +  utilizing the Serial Device Bus (serdev) interface.
> 
> serdev is Linux thingy, AFAIR. Please describe the hardware.

OK, in v2 it will get changed to:

"""
LIN transceiver, mostly hard-wired to a serial device, used for
communication on a LIN bus.
"""

> 
> > +
> > +  For more details on an adapter, visit: https://hexdev.de/hexlin#tty
> > +
> > +properties:
> > +  compatible:
> > +    const: linux,lin-serdev
> 
> Feels confusing. Your link describes real hardware, but you wrote
> bindings for software construct.
> 
> If you add this to DT, then it is hard-wired on the board, right?

Yes, it is hard-wired.

>  If so, how this could be a software construct?

It's not, but fairly generic, that's why I used 'linux,lin-serdev' as
compatible string. In v2 I'll change it to 'hexdev,lin-serdev'.

> > +
> > +required:
> > +  - compatible
> > +
> > +examples:
> > +  - |
> > +    &uart2 {
> 
> & does not make much sense here. I think you wanted it to be serial bus,
> so serial.

OK

> 
> > +      status = "okay";
> 
> Drop, it was not disabled anywhere.

OK

> 
> 
> > +      linbus {
> > +        compatible = "linux,lin-serdev";
> > +      };
> > +    };

Let me address these points, fix warnings from dt_binding_check and
reroll in v2.

Thanks
  -- Christoph